1. Field of the Invention
The present invention relates to a seat for vehicles and, in particular, to an improved connecting structure between a seat cushion and a seatback in a vehicle seat.
2. Description of the Related Art
Japanese Patent Laid Open Publication No. 58 (1983)-195508 discloses a type of seat for vehicles in which assembly of a seat cushion and a seat back is facilitated by interfitting brackets on the respective seat cushion and seat back. The brackets are provided with a self-engaging device for securing the interfitted brackets when the seat back is assembled with the seat cushion. The seat cushion bracket, which is fixed to the seat cushion, includes a control edge engagable by a cam surface on a hook member of double arms mounted on the seatback bracket fixed to the seatback. Upon assembling the seatback with the seat cushion, the seat cushion bracket is connected to a curved piece formed on the seatback bracket along a stop member which is mounted on the seatback bracket. As a result, the control edge and the cam surface on the hook member are engaged and the engagement maintained by the force of a spring interposed between the hook portion and the seatback bracket. Thus, the seatback bracket is supported by the seat cushion bracket simply by the connection of the respective brackets, thereby to attain the assembly of the seatback and the seat cushion.
However, the support of the seatback on the seat cushion is effected by the surface contact between the cam surface and the control edge in the above-mentioned seat for vehicles, so that dimensional tolerances in the cam surface and the control edge affect the support position and the support strength of the seatback. As a result, variations occur in the support position of the seatback and failure in the support of the seatback can occur in an extreme case. Therefore, high accuracy in the dimensions of the cam surface and the control edge is required, giving rise to increased machining time and manufacturing costs.